Its exalted, anything is possible Hypothetically.
Quick, keep all the elementals too busy being summoned to have time to increase their essence!
For thousands of years? Its not exactly instant you know.
I have speculated on a Templeship. Its a templeship to Treel which is not super super useful, but does mean he is invested enough to make help make it cheap!
Combine it with the Amoth City Smiting Cannon for a punch (why do you care if you leave derelicts when its not on your lawn, your allies can clean up their territory if they want) and the new Large Hanger with barracks for performing massive assaults against Blackstone Fortresses.
And when the crisis is done the smiting cannon can be removed and the ship refit with a cargo bay/stasis vault and so it can operate as a colony ship, actually utilizing its nature as a Treel Temple rapidly build new colonies.
102 before discounts, 66 Success after discounts, shipyard would halve that to 33. 9 of those 33 can come from a single Atelier Manse use. Another 9 can come from the Flawless Workshop. Exotic stockpiles can reduce the 33 by 5 each for up to two. So if you get a shipyard and throw everything at it, you could potentially build it by rolling 5 natural successes.
[Speaking of that. Anyone think it would be appropriate to make a short hand for this? Total success, amount from Atelier, amount from full on Factorums, usefulness of Exotic Material supplies. Just writing it is getting complicated but I know if I try force a short hand system I will end of explaining it every turn anyway. So any ideas]
So if you want to send a ship against Abaddon
Turn 45. Design Project for Templeship, Build shipyard or Templeforge. Produce as many naval phalanxes and assault rocs as possible.
Turn 46. Build Designed Templeship. Come up with awesome name. May sure you have at least 9 squadrons of Warbirds and Assault Rocs to go along, more Naval phalanxes!
Turn 47. Make sure you have at least 18 Logistics stockpiles and at least ten naval phalanxes per Assault Roc Squadron... at least.
Turn 48. Either twiddle thumbs while waiting for eldar ride or go on your own now in a epic whirlwind adventure.
Turn 49. Face Abaddon the Despoiler and Roc his world!
While there are a lot of ships and even a couple battleships being thrown around in this fight there are not so many that a Magical Heavy cruiser which can both act as an offbrand strike cruiser and can apparently throw ridiculously dangerous beam attacks that make Imperial Battleships super jelly. Especially when you can honestly say its just cause you wanted to do something useful with your colony ship during this crisis
Obviously you have some leeway to work with and could potentially use a more impressive ship by either going smaller or throwing more resources at it than this plan requires. Not that I consider a Geomantic Templeship mounting a macguffin weapon and over a hundred fighter craft and 150,000 Dragon Kings un-impressive by any standard.